The present disclosure relates to an image forming apparatus having a cache memory area (hereinafter, referred to as “font cache”) in which bitmap graphics of character fonts are stored.
A typical image forming apparatus that is a printer, a multifunctional printer, multifunctional peripheral equipment, or an MFP (Multifunction Peripheral) such as a multifunction machine or the like prints print data received from a PC (personal computer) or print data generated on the basis of document data of a read document from a reader, on a paper sheet or the like, thereby performing output (printout). The typical image forming apparatus converts a character font of the print data to bitmap graphics (raster-format data) and performs imaging (hereinafter, referred to as “rasterization”). However, when rasterization is performed each time a character font is converted to bitmap graphics, the processing takes much time. Thus, the typical image forming apparatus has a font cache, and bitmap graphics (hereinafter, referred to as “character images”) of character fonts are stored in the font cache. If a character image corresponding to a character font of print data has been stored in the font cache, it is possible to take out the character image from the font cache. Only if the corresponding character image has not been stored in the font cache, rasterization of the character font is performed. As described above, in the typical image forming apparatus having a font cache, storing of frequently-used character images in the font cache reduces the processing time in rasterization of a character font and allows for high-speed printout.
Such widespread use of a font cache in an image forming apparatus allows for high-speed printing. For example, a printer has been known in which: when print data is inputted from an external information processing apparatus, it is determined whether the print data falls within a character pattern formation range; and if the print data falls within the character pattern formation range and a character pattern of the print data has not been formed, the character pattern is formed and stored, and the same character pattern is prevented from being formed again, thereby increasing a printing speed. In addition, a printer has been known in which after data of a certain unit (e.g., 1 page) is received, it is checked how many times each font data is used in the page, and it is determined whether to create a cache/font, on the basis of the frequency of use, whereby it is possible to effectively create a cache/font. Moreover, a controller or a method has been known in which a buffer for LRU (Least Recently Used) delay processing is provided, update of a font cache is delayed, and deletion of a character pattern that is possibly used again in the near future is prevented, thereby improving printing performance.